Tag Archives: Labrador Retriever

Study demonstrates rapid decline in male dog fertility, with potential link to environmental contaminants

A study led by researchers at The University of Nottingham has discovered that the fertility of dogs may have suffered a sharp decline over the past three decades.

The research, published in the academic journal Scientific Reports, found that sperm quality in a population of stud dogs studied over a 26-year period had fallen significantly.

The work has highlighted a potential link to environmental contaminants, after they were able to demonstrate that chemicals found in the sperm and testes of adult dogs – and in some commercially available pet foods – had a detrimental effect on sperm function at the concentrations detected.

Semen study

Researchers believe that the latest results showing that dogs’ quality of semen has diminished may offer a new piece of the puzzle over the reported significant decline in human semen quality. Credit: © jurra8 / Fotolia

As ‘man’s best friend’ and closest companion animal, the researchers believe that the latest results may offer a new piece of the puzzle over the reported significant decline in human semen quality – a controversial subject which scientists continue to debate.

Dr Richard Lea, Reader in Reproductive Biology in the University’s School of Veterinary Medicine and Science, who led the research said: “This is the first time that such a decline in male fertility has been reported in the dog and we believe this is due to environmental contaminants, some of which we have detected in dog food and in the sperm and testes of the animals themselves.

“While further research is needed to conclusively demonstrate a link, the dog may indeed be a sentinel for humans – it shares the same environment, exhibits the same range of diseases, many with the same frequency and responds in a similar way to therapies.”

The study centred on samples taken from stud dogs at an assistance dogs breeding centre over the course of 26 years. Professor Gary England, Foundation Dean of the School of Veterinary Medicine and Science and Professor of Comparative Veterinary Reproduction, who oversaw the collection of semen said: “The strength of the study is that all samples were processed and analysed by the same laboratory using the same protocols during that time and consequently the data generated is robust.”

The work centred on five specific breeds of dogs – Labrador retriever, golden retriever, curly coat retriever, border collie and German shepherd – with between 42 and 97 dogs studied every year.

Semen was collected from the dogs and analysed to assess the percentage of sperm that showed a normal forward progressive pattern of motility and that appeared normal under a microscope (morphology).

Over the 26 years of the study, they found a striking decrease in the percentage of normal motile sperm. Between 1988 and 1998, sperm motility declined by 2.5 per cent per year and following a short period when stud dogs of compromised fertility were retired from the study, sperm motility from 2002 to 2014 continued to decline at a rate of 1.2% per year.

In addition, the team discovered that the male pups generated from the stud dogs with declining semen quality, had an increased incidence of cryptorchidism, a condition in which the testes of pups fail to correctly descend into the scrotum.

Sperm collected from the same breeding population of dogs, and testes recovered from dogs undergoing routine castration, were found to contain environmental contaminants at concentrations able to disrupt sperm motility and viability when tested.

The same chemicals that disrupted sperm quality, were also discovered in a range of commercially available dog foods – including brands specifically marketed for puppies.

Dr Lea added: “We looked at other factors which may also play a part, for example, some genetic conditions do have an impact on fertility. However, we discounted that because 26 years is simply too rapid a decline to be associated with a genetic problem.”

Over the past 70 years, studies have suggested a significant decline in human semen quality and a cluster of issues called ‘testicular dysgenesis syndrome’ that impact on male fertility which also include increased incidence of testicular cancer, the birth defect hypospadias and undescended testes.

However, declining human semen quality remains a controversial issue – many have criticised the variability of the data of the studies on the basis of changes in laboratory methods, training of laboratory personnel and improved quality control over the years.

Dr Lea added: “The Nottingham study presents a unique set of reliable data from a controlled population which is free from these factors. This raises the tantalising prospect that the decline in canine semen quality has an environmental cause and begs the question whether a similar effect could also be observed in human male fertility.”

Source:  University of Nottingham media release

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Limber tail – it’s more common than previously thought

Limber tail photo

Limber tail is a condition that affects mostly large working dog breeds.  It’s a distressing condition that causes the tail to become limp and painful and it’s official name is acute caudal myopathy.

A research team at the University of Edinburgh compared 38 cases of limber tail that were identified from owners’ reports about their dogs’ health with 86 dogs that had no tail symptoms.

Their goal was to gain insight into habits and lifestyle factors that might explain why some dogs are affected and not others.

The majority of dogs in the study were pets but those affected by limber tail were more likely to be working dogs, they found.

Swimming has previously been thought to be a risk factor for limber tail, which is sometimes known as ‘swimmers’ tail’. Some but not all of the affected dogs had been swimming prior to the onset of symptoms, the study found.

Dogs with the condition were more likely to live in northern areas, lending support to anecdotal reports that limber tail is associated with exposure to the cold.

Labradors that had suffered limber tail were more likely to be related to each other than unaffected dogs, which may indicate an underlying genetic risk.

Experts hope that further studies will identify genes associated with the condition, which could one day help breeders to identify animals that are likely to be affected. Over time, this could help to reduce the prevalence of the disease.

The symptoms usually resolve within a few days or weeks so many cases are not reported to vets. This may be why it has been so underestimated in the past. However, owners report that it can be very painful and distressing for the animals.

The study is the first large-scale investigation of limber tail and was conducted as part of the Dogslife project, which follows the health and wellbeing of more than 6000 Labradors from across the UK.  (Note:  the disorder also commonly affects English Pointers, English Setters, Foxhounds and Beagles.)

The study has been published in the Veterinary Record.

Source:  University of Edinburgh media release

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Wordless Wednesday, part 35

Wordless Wednesday, part 35

Oakley, by Army First Lieutenant Brandon Harker

BP_Wordless_wed_Hop_Logo_2014

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Wordless Wednesday, part 21

Nose kiss

First dementia dogs start work

The first ever “dementia dogs” who are specially trained to help people with early-stage dementia have started work in Scotland.

You can watch the story of Oscar, a Golden Retriever and Kaspa, the Labrador in this BBC News item:

What’s in your dog’s plastic toy?

A research team at Texas Tech University has studied the levels of phthalates and bisphenol A (known as BPA) in dog training batons and other plastic toys.  They presented their findings at the Society of Environmental Toxicology and Chemistry conference held in California.

The research was conducted by Kimberly Wooten, a master’s student using the project as her thesis, and Phil Smith, an associate professor of terrestrial ecotoxicology.  Smith also raises and trains Labradors.

“In the process of training a lab, you do a lot of work with these plastic bumpers. I have a lot of bumpers in my garage, and they spend a lot of time in the mouths of my retrievers. Well, lots of attention has been given to chemicals in plastics lately regarding their effects on humans. Since we all care about our dogs, and we want them to be as healthy and smart and well-behaved as possible, we decided to look into this.”

BPA are used to give elasticity to plastic and vinyl and are known endocrine disruptors that mimic estrogen or act as anti-androgens and could lead to negative health effects.  In 2012, the US Government banned the use of these chemicals in baby bottles.

Training bumpers had higher levels of BPA than toys; but weathered and aged toys released more BPA than newer ones.

The research raises a number of questions, but it is hard to compare results because so few studies have been done – particularly in the area of how much of the BPA actually enters the dog’s system.

“The interaction of pet health and environmental chemicals is understudied,” Wooten said. “What may be a safe dose for one species isn’t always a good measure for another species. But the amount of BPA and phthalates we found from the bumpers would be considered on the high end of what you might find in children’s toys.”

Source:  Texas Tech University press release

Hip dysplasia – it’s not just genetics

Doctoral research by Randi I. Krontveit at the Norwegian School of Veterinary Science has revealed that environmental factors play a larger role in the development of hip dysplasia than previously thought.

The critical period is from birth to the age of three months.  Activities such as walking up steps on a daily basis during this critical period increased the risk of developing hip dyplasia.

The study group consisted of 500 dogs in four breeds:  the Labrador Retriever, the Newfoundland, the Leonberger and the Irish Wolfhound.

Randi I. Krontveit with two of her study subjects. Photo courtesy of the Norwegian School of Veterinary Medicine

Environmental factors were assessed by questionnaires filled out by breeders and owners alongside examinations by veterinarians.  Dogs were followed for a period of ten years, making the findings of the study particularly robust.

Puppies born in the spring or summer and at breeders’ who lived on a farm or small holding had a lower risk of developing hip dysplasia.  After about eight weeks, the puppies began to live with their new owners. The opportunity to exercise daily in parks up until the age of three months reduced the risk of hip dysplasia.

Overall, it would appear that daily exercise out in gently undulating terrain up until the age of three months has a positive impact when it comes to preventing the disease.

For more information about this research, you can email Dr Krontveit via this page at the Norwegian School of Veterinary Medicine.